special effects

special effects, in motion pictures, cinematographic techniques that create illusions in the audience's minds as well as the illusions created using these techniques. Some common examples are the use of rear-screen projections, in which previously photographed material is projected behind the actors; the filming of miniature objects in such a way that they look life-size; and the use of animation techniques to create realistic looking scenes, creatures, or objects that can be combined with live action that has been filmed separately. Disaster films, horror movies, and science-fiction movies are three genres that often depend on elaborate special effects. Such effects were used dramatically in the Star Wars and Raiders of the Lost Ark series. See also motion-picture photography.